Buttress twist gage

ABSTRACT

The invention contemplates a vane-twist measuring or gaging instrument in which the overall twist of the vane is assumed to be indicated by the angular relation between a reference alignment, taken on one buttress surface, and a measured-offset alignment, taken on the corresponding surface of the other buttress for the same vane. Basically, a reference plane is established for the reference surface of the first abutment, as by using two fixed and precisely positioned spaced point-contact elements, and a gage carried by the instrument near the other buttress senses the inclination of the other buttress (with respect to the reference plane) when the other buttress is applied against a single, or third, fixed point of support on the instrument. In one form, the third support point is established by an elongated bar, with provision for central pivotal support, so that its angular orientation about the pivot may reflect contact with, and therefore slope of, the other vane buttress; in another form, the third support point is a fixed abutment near one end of the other buttress, and a probe responds to a given location near the other end of the buttress when the vane is applied to the three fixed support contacts.

Unite States Patent 1 Palmenberg 1 BUTTRESS TWIST GAGE [75] lnventor:Edward C. Palmenberg, Nanuet,

[73] Assignee: Chromalloy American Corporation, Orangeburg, NY.

[22] Filed: Dec. 29, 1971 [21] Appl. No.: 213,577

Related US. Application Data [62] Division of Ser. No. 25,506, April 3,1970.

Primary Examiner-Stanley N. Gilreath Assistant Examiner.lon W. HenryAttorney-Sandoe, Hopgood and Calimafde [57] ABSTRACT The inventioncontemplates a vane-twist measuring or gaging instrument in which theoverall twist of the vane is assumed to be indicated by the angularrelation between a reference alignment, taken on one buttress surface,and a measured-offset alignment, taken on the corresponding surface ofthe other buttress for the same vane. Basically, a reference plane isestablished for the reference surface of the first abutment, as by usingtwo fixed and precisely positioned spaced point-contact elements, and agage carried by the instrument near the other buttress senses theinclination of the other buttress (with respect to the reference plane)when the other buttress is applied against a single, or third, fixedpoint of support on the instrument. In'one form, the third support pointis established by an elongated bar, with provision for central pivotalsupport, so that its angular orientation about the pivot may reflectcontact with, and therefore slope of, the other vane buttress; inanother form, the third support point is a fixed abutment near one endof the other buttress, and a probe responds to a given location near theother end of the buttress when the vane is applied to the three fixedsupport contacts.

5 Claims, 7 Drawing Figures PATENTEU UEC 18 I975 SHEEI 3 OF 3 BUTTRESSTWIST GAGE This application is a division of my copending application,Ser. No. 25,506, filed Apr. 3, 1970.

'This invention relates to gaging and measuring devices for observingadherence to one of several dimen sional factors critical to theperformance of vanes in a turbine, such as the gas turbine of a jetaircraft.

Turbine-engine nozzle guide vanes or blades are subjected to rapidextremes of temperature and differential-pressure loading, and as aresult the individual parts comprising a nozzle assembly become bent andotherwise distorted. Moreover, vanes which have seen service conditions,with accompanying deformation, are often repaired and re-configured by ahot-forming technique, and unless extreme care is exercised, thisprocess can be another source of introducing angular deformation betweenthe mounting surfaces of the outer and inner buttresses of the guidevane.

Such departures from new part dimensions prevent proper fitting of thevane into the support mechanism or shroud assembly; they also create afalse angle of attack by the vane airfoil section or blade. Both theseconditions are unsuitable for proper engine performance.

The deformations and distortions which are deleterious to engineperformance include others beyond the overall-twist factor noted above.But I have discovered that buttress-to-buttress twist in a turbine vaneis a single factor of critical importance, and the present invention isparticularly concerned with the gaging and measurement of this factor.

It is accordingly an object of the invention to provide means formeasuring or gaging twist, or departures from desired twist, in vanestructures of the character indicated.

Another object is to achieve the above object with a device which, for agiven vane configuration, is sensitive essentially only and criticallyto the twist factor.

It is a specific object to achieve the foregoing with basically simplestructure which lends itself to reliable use by relatively unskilledpersonnel and which enables the accurate checking of every vane element,before and after reconditioning.

Another specific object is to provide instrumentation to achieve theforegoing and having the inherent capability of assuring products which,insofar as the twist factor is concerned, equal or exceed theconsistency and quality of newly manufactured vanes.

Other objects and various further features of novelty and invention willbe pointed out or will occur to those skilled in the art from a readingof the following specification, in conjunction with the accompanyingdrawings. In said drawings, which show, for illustrative purposes only,various forms of the invention:

FIG. I is an overall perspective view of a preferred Briefly stated, theinvention contemplates a vanetwist measuring or gaging instrument inwhich the overall twist of the vane is assumed to be indicated by theangular relation between a reference alignment, taken on one buttresssurface, and a measured-offset alignment, taken on the correspondingsurface of the other buttress for the same vane. Basically, a referenceplane is established for the reference surface of the first abutment, asby using two fixed and precisely positioned spaced point-contactelements, and a gage carried by the instrument near the other buttresssenses the inclination of the other buttress (with respect to thereference plane) when the other buttress is applied against a single, orthird, fixed point of support on the instrument. In one form, the thirdsupport point is established by an elongated bar, with provision forcentral'pivotal support, so that its angular orientation about the pivotmay reflect contact with, and therefore slope of, the other vanebuttress; in another form, the third support point is a fixed abutmentnear one end of the other buttress, and a probe responds to a givenlocation near the other of the buttress when the vane is applied to thethree fixed support contacts.

Referring to FIGS. I and 2 of the drawings, the invention is shown inapplication to a twist-measuring or gaging instrument, for observingtwist between the two buttresses 10-11 of a jet-engine nozzle vane 12(see also FIG. 1A); the blade 13 of the vane is integral with thebuttresses 10-11. Each of the buttresses includes opposed abutmentsurfaces or edges 14-15, extending between end surfaces 16-17. In theengine-assembly of such vanes, for a given engine stage, such afirst-stage assembly using blades 12, corresponding abutment surfacesl4-l5 (14-l5') of adjacent outer and inner buttresses are abutted tocomplete a circumferentially continuous succession, the assembly beingretained by shroud means (not shown) located and locked as by retaininglugs 18-18 and slot 19, as will be understood.

The instrument comprises a flat rigid frame or base with support meansat one end for one buttress and with separate support means at the otherend, for the other buttress. As shown, the surface 14 of the outerbuttress l0 isgiven reference-plane support, and twist is evaluated byobserving slope of the corresponding surface 14' at the support for theinner buttress 11.

The instrument comprises a flat rigid base or frame 20 carrying theindicated support means. At the left end, the fixed plane of referenceis established by spaced upstanding abutments, shown as hard pins 21-22fixed to base 20 and conveniently ground to precisely the same elevationabove the bottom face or plane of the base 20. The buttress surface 14is engaged and positioned by the pins 21-22 at the reference plane. Insimilar fashion, at the other end, a third such pin 23 is fixed to base20 and is ground off to determine a point of support near one end of thecorresponding surface of buttress 11. These three points of support makefor an unambiguous setting of the vane 12 via both buttresses thereof,so that a probe element or rocker arm 24 associated with a gage, such asan indicator 25, may detect vane twist by observing the elevation at apreselected location near the other end of the buttress surface 14.

For assurance that each of a succession of vanes 12 will be positionedat precisely corresponding locations, the left support means includes anupstanding end abutment 26 for location of the buttress end 17, and anupstanding end abutment 27 for Similar location of the buttress end 17.The abutment 27 may be a bracket 28, bolted at 29 to base 20, andtruncated along a surface 30 which is inclined in accordance with theslope of the end 17 of the buttress to be accommodated. A hardenedpin orrod insert 31, extends substantially parallel to the elongation axis 13of the span of the blade 13 and is located centrally of the truncatedsurface 30, so that locating abutment for the end 17 is essentially asingle point or line contact and is thus essentially independent ofsurface irregularities in the entire surface 17. Preferably, thetruncation 30 extends short of the outer end of bracket 28, to providemore secure and unquestionably referenced location of the insert rod 31.The truncation 30 may be milled after drilling the bore for rod 31, andbefore force-fitting the rod 31 into its bore; and the plane oftruncation preferably intersects the rod-support bore short of cuttingthe bore axis, thereby assuring continuous support of rod 31 along itsentire length. In similar fashion, but at an appropriately offsetlocation, an insert rod 31 in a truncated surface 30 of abutment 27determines a singlecontact reference location for the buttress end 17.The final component of vane-positioning location may be determined by asingle pin 32, fixed to base 20 and rising above the reference plane ofpins 31-22, for edge contact with the recessed outer surface 10 of thebuttress 10.

To recapitulate: the three pins 21-22-23 establish a fixed generallyhorizontal plane of orientation and, thus, a first component forstabilized location of vane 12 The two abutment rods 31-31 establish afixed direction of the blade-elongation axis 13' (above said plane) and,thus, a second component for stabilized location of vane 12. Finally,the single pin 32 establishes a left-most location of the buttress 10,to determine the third component for location of vane 12 on the base 20.When the instrument is laid upon or secured to a horizontal table, it isa simple matter for an unskilled operator to apply and press eachsuccessive blade into the described abutment relation at21-22-23-3l31'32; in fact, the described placement is naturally adaptedto a left-hand grasping of the vane, leaving the right hand free, torecord observed indications.

in the form shown, the gage is a conventional indicator, having arotatable dial to permit a setting of zero,

7 from which plus and minus abnormalities may be directly read throughdisplacement of the indicator needle. The indicator 25 may include arounded probe tip 33, spring-urged to extended position. The body ofindicator 25 is secured to base 20 by a bracket 34, the bottom of whichis grooved at 35 to accommodate movement of the rocker arm or lever 24bywhich the indicator probe 33 tracks the other end of the buttresssurface 14', i.e., the end opposite that which is fixedly referencedat23. Arm 24 rocks about a pivot pin at 36. A bottom dowel 37 limits theextent to which it can be rocked in one direction, by the spring-loadedaction of probe tip 33, and a rod or pin insert 38 projects sufficientlyabove the upper surface of arm 24 to establish a single contact with thebuttress surface 14.

Normally, before a vane is placed on the instrument, the resilientloading of tip 33 establishes a raised position of the buttress-trackingcontact 38 (see FIG. 2, where the indicator needle is negatively offsetfrom the zero position). Placement of the vane 12, as described, causessurface 14 to downwardly displace contact 38,

thus driving the probe tip 33 upwardly. The extent of upward drive isindicated at 25, and this indication may involve quantitative display ofdeparture from normal, if the dial at 25 is appropriately preset. Thus,the zero indication shown in FIG. 1 means a correct angular offset orslope of surface 14' with respect to surface 14, meaning a correctoverall twist in the vane 12. And depending on the degree and directionof observed departure from this preset or zero condition, correctivemeasures must be taken in the hot-forming operation, before a vane canbe considered acceptable.

In the instrument of FIGS. 3 and 4 (see FIG. 1A for buttress surfaces),the buttress surface 14 is fixedly referenced by an inclined flatsurface or edge 40 formed in the upstanding side plate 41 of thebench-mountable instrument in which the probe tip 42 of an indicator 43directly tracks the unsupported end of the surface 14' of the innerbuttress. The frame comprises a rectangular base plate 44, to oppositeends of which the upstanding side walls or plates 41-45 are bolted; acentral upstanding spacer plate 46 assures frame rigidity. The referenceplane for surface 14 may be established at two spaced rod-insertcontacts along the length of the inclined edge 40, but in the form shownthe edge 40 directly locates surface 14. The adjacent end 17 may locateagainst a single-contact rod insert 47 in another edge 48 of plate 41,the inclination between edges 41-48 being appropriate to the particularbuttress to be tested and observed. An edge locator or projection 49defines a stop for right-ward limiting location of the outer edge of end17. At the left-hand end, in FIGS. 3 and 4, fixed parallel pins 50-51carried by side plate 45 provide fixed bottoming reference for buttressend 17 and for the nearby buttress surface 14', and the fixed mountingof the body of gage 43 to side plate 45 is preferably such as to alignthe axis of probe 42 substantially perpendicular to the buttress surface14. Of course, the resiliently urged normally outward position of theprobe tip 42 is such as to intercept the adjacent end of buttresssurface 14, for the most extreme anticipated vanewarp condition. y

In operation, the vane 12 is applied to the instrument, holding surface14 against the reference-plane edge 40, with bottoming contact at47-50-51, and with leftward limiting contact at 49. The probe tipdisplacement may read quantitatively, as departures from normal (zeropreset) or as absolute magnitudes, if the gage indicator 43 is suitablycalibrated.

The instrument of H6. 5 makes twist-gage measurements on a second-stagevane (suggested by phantom outline 54) and resembles that of FIGS. 1 and2 in several respects, but is differs by employing a rocker arm 55 atthe means of both locating the adjacent vane buttress and of detectingthe slope or warp thereof. The base plate 56 is slotted at 57 toaccommodate pivoted movement of rocker arm 55 about its fixed pivot 58,and parallel rod inserts 59-60 are provided in the upper surface of arm55 at positions astride the pivot axis to assure stabilized contact withthe buttress surface (corresponding to 14' in FIG. 1A). A bracket 61fixedly mounts the body of the indicator 62, so that the probe tipthereof may track the end of the rocker arm 55, in the manner describedfor arm 24 in FIGS. 1 and 2. As shown, the upper surface of arm 55 ischaracterized by a slope or ramp, and the far buttress end locatesagainst a single contact rod 63, embedded in an upstanding wall 64,which makes with the down slope of the ramp an angle substantiallymatching that between the buttress end and abutment surfaces to belocated thereon. A stop pin 65, carried by the base 56, limits downwardrocking of arm 55 due to spring action within the probe tip 62' ofindicator 62.

At the fixed or reference-plane end of the instrument, spaced fixedstuds 66-67 are ground off to determine the reference plane for theabutment surface of the other buttress. An end bracket 68 is bolted tobase plate 56 and rises above the ends of studs 66-67; locating dowels68'-68" assure permanent angular reference of bracket 68 to the baseplate 56. Bracket 68 is locally recessed at 69 to define an upstandingreference wall 70 for the left-buttress end, diagonally opposite theright-buttress end which locates at rod-insert 63.

In using the instrument of FIG. 5, the vane 54 is positioned in much thesame manner as already described, except that the manualcounterclockwise torque applied to the vane is relied upon to drive theinnerbuttress end (16') and surface (14) firmly against abutmentcontacts 63-59-66 on the rocker arm 55. Final stability for theorientation of vane 54 is achieved when the end lugs or feet 72-73 ofthe outer buttress abut the surfaces 70-74, at which point there may bea slight clearance at 72-69, respectively. At this juncture, thereference-plane surface (14) at the outer buttress is held against pins66-67, and the rocker arm 55 has assumed the slope of the inner-buttresssurface (14'), so that the indicator reading can be noted.

In constructing the described instruments, the base plates, brackets andother elements which serve only for mounting, such as brackets27-28-34-49-61 and the rocker arms, are conveniently made of flat groundlow-carbon steel. On the other hand, the abutment elements, such asinsert rods, positioning studs and pins, and abutment brackets (e.g., at68) are made of tool steel, hardened for example to Rockwell C 58-60.

FlG. 6 illustrates a further embodiment, suitable formaking twistobservations on a vane of the type shown in FIG. 1A. A rocker arm 75employs hard pin inserts 76-77 as single-point contacts (for surface14') on opposite sides of the pivot pin 78. The tail end of arm 75 istracked by the probe tip of the indicator, which may be mounted andconstructed as in FIG. 5 and which is therefore given the same referencenumbers. As also shown in FIG. 5, the base 79 is slotted (at 80) toaccommodate the rocker arm (75), and bracket means 81 is mounted at theother end of the base, to locate the outer buttress As shown, bracketmeans 81 is L- shaped, with an inclined ramp 82 against which toreference the sloping end surface 17. A similar slope 83 on anupstanding end 84 of the rocker arm 75 similarly serves thecorresponding end surface (17') of the inner buttress.

In FIG. 6, simplicity is achieved by making the base 79 and the bracket81 of tool steel, thereby reducing the number of hardened inserts. Inuse, the vane 12 is applied to lay surface 14 flat on base 79 and urgedleftward and forward into limiting contact with the inside corner walls82-82 of the L bracket 81. The inner buttress is pressed to align thecontacts 76-77 with surface 14', while drawing end surface 17' againstthe slope 83. At this point, the indicator 62 is read, for possibledeparture from normal (zero).

The described constructions have been found to reliably measure buttresstwist (i.e., overall vane twist) on individual vanesthat arereconditioned, straightened or rebuilt. These constructions meet thestated objects and have reliably served in hundreds of thousands ofgaging operations, without noticeable wear. The products whichsuccessfully pass the instrument have demonstrated at least as greatperformance capability as do newly manufactured, unused originalproducts. All testing-and gaging can be readily performed by relativelyunskilled personnel, on a go no-go" basis for each observed vane.

While the invention has been described in detail for the forms shown, itwill be understood that modifications and adaptations may be madewithout departure from the scope of the invention.

What is claimed is:

l. Gage means for observing buttress-to-buttress twist in an appliedturbine vane having a span extending between integral outer and innerbuttresses, each of said buttresses having opposed substantially flatelongated abutment surfaces for nested abutment with correspondingadjacent surfaces of the next adjacent vane when in shrouded assemblyabout a turbine axis, said buttresses also having opposed substantiallyflat end surfaces which align in spaced axial-end planes when inshrouded assembly, said gage means comprising a rigid frame withouter-buttress support means spaced from inner-buttress support meansfor supporting the turbine vane only at the outer and inner buttressesthereof; one of said support means comprising first fixed referenceabutment means adapted to engage one buttress and to locate the sameagainst rotation with respect to the vane-span elongation axis, fixedaxial-locating means operative to axially contact a buttress and thusaxially locate the vane against movement at least in one direction ofthe vane-span elongation axis, the other of said support meanscomprising further fixed reference abutment means adapted to engage oneof the abutment surfaces of the other buttress at one location alongsaid one other-buttress surface, and at a location along an adjacentflat end surface of said other buttress said further reference abutmentmeans having a convex buttress-contacting surface that is arcuate aboutan axis substantially parallel to the vane-span elongation axis, and aframe-mounted probe offset from said arcuate surface and positioned foryieldably movable contact with an abutment surface if said otherbuttress when the applied vane is fixedly abutted to said first andfurther fixed abutment means.

2. Gage means according to claim I, in which said probe comprises amechanical-displacement indicator having a body fixed to said frame andprobe-element means including an element poised for substantiallysingle-contact engagement with part of an applied vane buttress.

3. Gage means according to claim 1, in which said further fixedreference abutment means comprises two spaced fixed cylindrical rods onaxes that are substantially parallel to the vane-span elongation axis.

4. Gage means according to claim 1, in which said fixed axial locatingmeans is part of said rigid frame.

5. Gage means for observing buttress-to-buttress twist in an appliedturbine vane having a span extending between integral outer and innerbuttresses, each of said buttresses having opposed substantially flatelongated abutment surfaces for nested abutment with correspondingadjacent surfaces of the next adjacent vane when in shrouded assemblyabout a turbine axis, said locate the same against rotation with respectto the vane-span elongation axis, fixed axial-locating means operativeto axially contact a buttress and thus axialiy locate the vane againstmovement at least in one direction of the vane-span elongation axis, theother of said support means comprising further fixed reference abutmentmeans adapted to support one of the abutment surfaces of the otherbuttress at one location along said one other-buttress surface and at alocation along an adjacent flat end surface of said other buttress, saidfurther fixed reference abutment means comprising two spaced fixedcylindrical rods on axes that are substantially parallel to thevane-span elongation axis, said rods being adapted to engage and supportsaid other buttress at said respective locations, and a framemountedprobe offset from said arcuate surfaces and positioned for yieldablymovable contact with an abutment surface of said other buttress when theapplied vane is fixedly abutted to said first and further fixed abutmentmeans.

1. Gage means for observing buttress-to-buttress twist in an appliedturbine vane having a span extending between integral outer and innerbuttresses, each of said buttresses having opposed substantially flatelongated abutment surfaces for nested abutment with correspondingadjacent surfaces of the next adjacent vane when in shrouded assemblyabout a turbine axis, said buttresses also having opposed substantiallyflat end surfaces which align in spaced axial-end planes when inshrouded assembly, said gage means comprising a rigid frame withouterbuttress support means spaced from inner-buttress support means forsupporting the turbine vane only at the outer and inner buttressesthereof; one of said support means comprising first fixed referenceabutment means adapted to engage one buttress and to locate the sameagainst rotation with respect to the vane-span elongation axis, fixedaxial-locating means operative to axially contact a buttress and thusaxially locate the vane against movement at least in one direction ofthe vane-span elongation axis, the other of said support meanscomprising further fixed reference abutment means adapted to engage oneof the abutment surfaces of the other buttress at one location alongsaid one other-buttress surface, and at a location along an adjacentflat end surface of said other buttress said further reference abutmentmeans having a convex buttress-contacting surface that is arcuate aboutan axis substantially parallel to the vane-span elongation axis, and aframe-mounted probe offset from said arcuate surface and positioned foryieldably movable contact with an abutment surface if said otherbuttress when the applied vane is fixedly abutted to said first andfurther fixed abutment means.
 2. Gage means according to claim 1, inwhich said probe comprises a mechanical-displacement indicator having abody fixed to said frame and probe-element means including an elementpoised for substantially single-contact engagement with part of anapplied vane buttress.
 3. Gage means according to claim 1, in which saidfurther fixed reference abutment means comprises two spaced fixedcylindrical rods on axes that are substantially parallel to thevane-span elongation axis.
 4. Gage means according to claim 1, in whichsaid fixed axial locating means is part of said rigid frame.
 5. Gagemeans for observing buttress-to-buttress twist in an applied turbinevane having a span extending between integral outer and innerbuttresses, each of said buttresses having opposed substantially flatelongated abutment surfaces for nested abutment with correspondingadjacent surfaces of the next adjacent vane when in shrouded assemblyabout a turbine axis, said buttresses also having opposed substantiallyflat end surfaces which align in spaced axial-end planes when inshrouded assembly, said gage means comprising a rigid frame withouter-buttress support means spaced from inner-buttress support meansfor supporting the turbine vane only at the outer and inner buttressesthereof; one of said support means comprising first fixed referenceabutment means adapted to engage one buttress and to locate the sameagainst rotation with respect to the vane-span elongation axis, fixedaxial-locating means operative to axially contact a buttress and thusaxially locate the vane against movement at least in one direction ofthe vane-span elongation axis, the other of said support meanscomprising further fixed reference abutment means adapted to support oneof the abutment surfaces of the other buttress at one location alongsaid one other-buttress surface and at a location along an adjacent flatend surface of said other buttress, said further fixEd referenceabutment means comprising two spaced fixed cylindrical rods on axes thatare substantially parallel to the vane-span elongation axis, said rodsbeing adapted to engage and support said other buttress at saidrespective locations, and a frame-mounted probe offset from said arcuatesurfaces and positioned for yieldably movable contact with an abutmentsurface of said other buttress when the applied vane is fixedly abuttedto said first and further fixed abutment means.